Eric Daman has a wall of bags and shoes tochoose from when dressing the cast of “Gossip Girl.” Photo: Elizabeth Lippman

‘Clothes make the man,” said Mark Twain. “Naked people have little or no influence on society.” Oh if the literary genius could see Blair and Serena now, climbing their way up the Upper East Side social ladder one couture-clad step at a time.

Those who tune in to “Gossip Girl” on Monday nights do so not only for a “look inside the scandalous lives of Manhattan’s elite” and their feisty threesomes and untold family secrets, but also for the fashion. Ah, the fashion!

The man responsible for clothing the cast — which usually amounts to about 80 costumes an episode — is Eric Daman, head costume designer and stylist extraordinaire, who’s espousing his credo in the new style book “You Know You Want It” (Clarkson Potter, $29.99), out now.

“It’s a fantasyland to have fun in,” says Daman of the drama series. And so is the show’s wardrobe closet. Tucked away inside a warehouse studio on a bleak block in industrial Long Island City are walls of bags (organized by color), boxes of shoes (organized by size) and baskets of headbands (for Blair!), bow ties (for Chuck!) and drawers of tights, gloves and everything in between.

Daman invited The Post into the most coveted dressing room in town to talk trends for the new year. How to turn those fleeting fads into timeless fashion, however, is up to you.

“Instead of compiling your list of perfect must-haves solely from the mannequins in shop windows,” he says in the book, “see what experiences you have had that make you unique, and then incorporate them into your personal style.”

Still, a girl needs a little guidance and Daman’s eager to give it. The “it” being all that’s haute under the style sun.